A conventional bicycle rear wheel comprises a rear wheel hub to one side of which is fitted a set of sprockets for a driving chain. Hub flanges on either side of the hub are connected by wire spokes under tension with a conventional tire-carrying rim. The rear wheel rim is the same as is used on the front wheel of the bicycle in question.
The presence of the sprocket set in a conventional rear wheel leads to an undesired lateral displacement of the center plane of both hub flanges from the rim center plane toward the opposite side from the sprocket. As a result of this roughly 5 to 10 mm displacement, which is known as the amount of dish, the tension on the sprocket-side spokes is greater than that of the spokes on the side away from the sprocket to an extent which greatly reduces the stability of the rear wheel. This is the most important problem with bicycle rear wheels and it has been known for decades. It is therefore desirable to bring about an optimum balance of the spoke tensions on the two rear wheel sides.
French patent application 76 22859 solves this problem by a lateral displacement of the center plane of both hub flanges in rear wheels toward the sprocket side, the rim position in the center plane of the frame being retained. Both hub flanges are then at the same distance from the rim center plane and the spoke tensions on both wheel sides are therefore completely compensated, as is each bicycle front wheel. Wide use of this system has not hitherto been possible due to the necessarily complicated bicycle frame with an asymmetrical rear frame.
Recently, the press has disclosed new and very expensive carbon rims. In the rear wheel rim the high torsional rigidity of the rim profile permits anchoring of the spokes laterally displaced from the rim center toward the sprocket side, unlike the front wheel rim, in which there is conventionally symmetrical anchoring of the spokes. Thus, unlike the aforementioned solution, this measure with respect to the rear wheel only partly balances the unequal spoke tensions on both wheel sides. Nevertheless, a rear wheel equipped with such a rim can be used in any conventional symmetrical bicycle frame. However, it is a vital requirement for this solution that the rim be extremely stiff.